And, devilsknew, I do feel your pain. I suspect what annoys you about mango chutney is the same thing that annoys me about people putting cranberries in biscotti. (I’m Italian.)
However, to be quite succinct: When I said “a common ingredient in chutneys”, my actual mental parsing was – chutneys that you encounter – what are they often made of?
And, since I am in America, I myself said “mango” because I figured that’s what most people would have encountered.
However, I personally have made chutney with just about every fruit under the sun except tomatoes. I love it with roasted meat. I love it with poultry. I love it with fish.
Believe me, I was equally baffled when everybody said, “conch”.